We present new reddening maps of the Small and Large Magellanic Cloud based on the data of the third phase of the Optical Gravitational Lensing Experiment ( OGLE III ) .
We have used two different methods to derive optical reddening maps .
We adopt a theoretical mean unreddened colour for the red clump in the SMC and LMC , respectively .
We subdivide the photometric data for both Clouds into subfields and calculate the difference between the observed red clump position and the theoretical value for each field , which provides us with the reddening value in ( V - I ) .
Furthermore reddening values are obtained for 13490 LMC RR Lyrae ab and 1529 SMC RR Lyrae ab stars covering the whole OGLE III region of the MCs .
The observed colours ( V - I ) of the RR Lyrae stars are compared with the colour from the absolute magnitudes .
The absolute magnitude of each RR Lyrae star is computed using its period and metallicity derived from Fourier decomposition of its lightcurve . In general we find a low and uniform reddening distribution in both Magellanic Clouds .
The red clump method indicates a mean reddening of the LMC of E ( V - I ) = 0.09 \pm 0.07 mag , while for the SMC E ( V - I ) = 0.04 \pm 0.06 mag is obtained .
With RR Lyrae stars a median value of E ( V - I ) = 0.11 \pm 0.06 mag for the LMC and E ( V - I ) = 0.07 \pm 0.06 mag for the SMC is found .
The LMC shows very low reddening in the bar region , whereas the reddening in the star-forming leading edge and 30 Doradus is considerably higher .
In the SMC three pronounced regions with higher reddening are visible .
Two are located along the bar , while the highest reddening is found in the star-forming wing of the SMC .
In general the regions with higher reddening are in good spatial agreement with infrared reddening maps as well as with reddening estimations of other studies .
The position-dependent reddening values from the red clump method are available via the German Astrophysical Virtual Observatory interface at http : //dc.zah.uni-heidelberg.de/mcx